Five set bias in tennis

Model, Sport Models | | June 21, 2010 at 3:43 pm

federerWith Wimbledon just about to start, it is interesting that not many people know or understand the dynamics between a 5 set and 3 set match. Only 4 times a year, not including a couple of one-off finals matches are 5 set matches held for men, and the difference between betting favourites and underdogs on 5 set matches is vastly different to the best of 3 set format.

Truth is, that with a 5 set match, a favourite is more likely to win the match. It makes perfect sense. If you consider a player and a probability to win a certain point, then one can easily calculate the probability to win the game, set and then match. The more sets in the match, the more likely that a person is going to win if his probability of winning a point is higher.

For example, if a player is a 55% chance to win any point on serve, whilst their opponent is only a 50% chance to win any point on serve, then the first mentioned player is a 75.1% chance to win the match for a best of 3 sets match, and a 79.9% chance to win the match for a best of 5 set match.

The difference may not seem like a lot, but it is enough to get enough people confused.

Data over the past 6 years has shown that actually betting on the favourites in a 5 set match without any other information is in fact profitable. With a database of nearly 3000 bets, if one were to bet to win $500 on every match, then should all the bets be on the favourite, then you would have made a very handy 2.1% ROI. This equates to a profit of $224,383.00. Pretty nice indeed.

On the other hand, had you bet to win $500 of every underdog in a 5 set match, then you would have seen yourself out of pocket 10.3% ROI, or a loss of $58,621. Ouch. Interestingly the win amount is greater than the loss because of some large bets on short priced favourites.

Also, if one were to bet $500 straight up on all the favourites of 5 set matches, then one would have made 1.5% ROI or $20,855 over the past 5-6 years. Losses of 22.7% ROI or a massive loss of $321,230 would have been made if one were simply betting on the underdog at $500 a pop.

These are incredible numbers, and goes to show that the general public underrate the favourite when it comes to 5 set betting. Keep this in mind when betting on a favourite at Wimbledon.

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10 Comments

  1. Hareeba says:

    And a classic example first up!!
    Fed would be on his way home from SW19 by now if it had been best of 3

  2. mark says:

    One slight error (I think?) – the 75.1% chance you mention is for a 3-set advantage match while the 79.9% is for a 5-set tiebreaker match.

    A 5-set advantage match is 80.04% by my reckoning which marginally magnifies the point you were making.

  3. sportpunter says:

    correct mark, the 75.1% goes down to 74.9%

  4. Brett says:

    So would this extrapolate to an automatic profit on the 3-0 set line for the favourite?

  5. sportpunter says:

    you would think so brett, I dont have the set odds to test

  6. plsmove says:

    I am confused as I cant figure out a meaning of this article. What confuses me most is what is difference between 2 sentences belows? What do we bet on in each of them becasue as I understand now it is the same things. Thanks

    1) With a database of nearly 3000 bets, if one were to bet to win $500 on every match, then should all the bets be on the favourite, then you would have made a very handy 2.1% ROI

    2) Also, if one were to bet $500 straight up on all the favourites of 5 set matches, then one would have made 1.5% ROI or $20,855 over the past 5-6 years

  7. admin says:

    It simply means that without any other information, if you simply bet on the favourite in every best of 5 set match, then you would have made a very handy 2% ROI. There is a bias there, that indicates that favourites in these matches seem to win a lot more often than the odds, and hence general public, percieve.

  8. plsmove says:

    OK, thanks. It is my understanding of first sentence that I quote. But I am confused if the second sentence expresses the same? If yes, why it is 1.5% roi there and 2.1% in first one.

  9. admin says:

    the first one is betting to win $500, the second one is betting a flat $500

  10. plsmove says:

    OK, this makes perfect sense now!

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